/*
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.xebia.commons.logging;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogConfigurationException;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.impl.Log4JLogger;
import org.apache.log4j.Logger;

/**
 * <p>
 * Concrete subclass of {@link LogFactory} specific to log4j. This is an altered
 * copy of org.apache.commons.logging.impl.Log4jFactory. This class was flagged
 * deprecated in commons-logging-1.1.1
 * Despite deprecation (removed here), this is a useful class in circumstances where
 * you have to rely on the "service-id" method of determining the logger
 * implementation (see commons-logging). IE. in Websphere 6. This class can be
 * used next to commons-logging 1.0.4 - 1.1.1 and all versions of log4j
 * 
 * @author Sander Hautvast
 * @author Costin Manolache
 */
public final class Log4jFactory extends LogFactory {

	private final static Log4jBootstrap log4jBootstrap;
	
	static {
		System.out.println("INFO: Starting commons-logging and log4j");
		log4jBootstrap = Log4jBootstrap.startLogging();
	}

	public Log4jFactory() {
		super();
	}

	/**
	 * The configuration attributes for this {@link LogFactory}.
	 */
	private Hashtable attributes = new Hashtable();

	// Previously returned instances, to avoid creation of proxies
	private Hashtable instances = new Hashtable();

	// --------------------------------------------------------- Public Methods

	/**
	 * Return the configuration attribute with the specified name (if any), or
	 * <code>null</code> if there is no such attribute.
	 * 
	 * @param name
	 *            Name of the attribute to return
	 */
	public Object getAttribute(String name) {
		return (attributes.get(name));
	}

	/**
	 * Return an array containing the names of all currently defined
	 * configuration attributes. If there are no such attributes, a zero length
	 * array is returned.
	 */
	public String[] getAttributeNames() {
		Vector names = new Vector();
		Enumeration keys = attributes.keys();
		while (keys.hasMoreElements()) {
			names.addElement((String) keys.nextElement());
		}
		String results[] = new String[names.size()];
		for (int i = 0; i < results.length; i++) {
			results[i] = (String) names.elementAt(i);
		}
		return (results);
	}

	/**
	 * Convenience method to derive a name from the specified class and call
	 * <code>getInstance(String)</code> with it.
	 * 
	 * @param clazz
	 *            Class for which a suitable Log name will be derived
	 * 
	 * @exception LogConfigurationException
	 *                if a suitable <code>Log</code> instance cannot be
	 *                returned
	 */
	public Log getInstance(Class clazz) throws LogConfigurationException {
		Log instance = (Log) instances.get(clazz);
		if (instance != null)
			return instance;

		instance = new Log4JLogger(Logger.getLogger(clazz));
		instances.put(clazz, instance);

		return instance;
	}

	public Log getInstance(String name) throws LogConfigurationException {
		Log instance = (Log) instances.get(name);
		if (instance != null)
			return instance;

		instance = new Log4JLogger(Logger.getLogger(name));
		instances.put(name, instance);

		return instance;
	}

	/**
	 * Release any internal references to previously created {@link Log}
	 * instances returned by this factory. This is useful in environments like
	 * servlet containers, which implement application reloading by throwing
	 * away a ClassLoader. Dangling references to objects in that class loader
	 * would prevent garbage collection.
	 */
	public void release() {
		instances.clear();
		if (log4jBootstrap != null) {
			log4jBootstrap.stopLogging();
		}
	}

	/**
	 * Remove any configuration attribute associated with the specified name. If
	 * there is no such attribute, no action is taken.
	 * 
	 * @param name
	 *            Name of the attribute to remove
	 */
	public void removeAttribute(String name) {
		attributes.remove(name);
	}

	/**
	 * Set the configuration attribute with the specified name. Calling this
	 * with a <code>null</code> value is equivalent to calling
	 * <code>removeAttribute(name)</code>.
	 * 
	 * @param name
	 *            Name of the attribute to set
	 * @param value
	 *            Value of the attribute to set, or <code>null</code> to
	 *            remove any setting for this attribute
	 */
	public void setAttribute(String name, Object value) {
		if (value == null) {
			attributes.remove(name);
		} else {
			attributes.put(name, value);
		}
	}

}
